I remember a few from various stages of my life (born 1984).
Seeing the demo footage of Sonic 2 in Woolworths and thinking the leaves falling down in Aquatic Ruin zone was so cool and advanced.
The original Sega arcade of Virtua Racing with the moving cars completely blew me away.
I remember my uncle loading up Cannon Fodder on his Amiga, and a REAL song with REAL music came out, along with REAL photos. I was amazed haha.
A few years on I remember a PlayStation demo disc having promo footage of the first Gran Turismo and it looked so real to me, I watched it over and over. The first Driver on PS1 looked absolutely amazing to me also.
Playing Call of Duty World at War for the first time, if that counts as retro. I had always played co-op games with my brother, and when he was gone for a weekend, I decided to try and play for myself. Spent countless hours replaying missions until I finally beat the campaign. And if I remember correctly, it drops you straight into zombies with no warning. I remember it being way past my bedtime, sitting alone in the dark. I was absolutely terrified because I was genuinely shocked by the premise and maybe too young for something so scary. Didn’t sleep at all that night.